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Impaired spatial working memory (SWM) is a robust feature of schizophrenia and has been linked to the risk of developing psychosis in people with an at-risk mental state (ARMS). We used functional magnetic resonance imaging (fMRI) to examine the neural substrate of SWM in the ARMS and in patients who had just developed schizophrenia.

Method

fMRI was used to study 17 patients with an ARMS, 10 patients with a first episode of psychosis and 15 age-matched healthy comparison subjects. The blood oxygen level-dependent (BOLD) response was measured while subjects performed an object–location paired-associate memory task, with experimental manipulation of mnemonic load.

Results

In all groups, increasing mnemonic load was associated with activation in the medial frontal and medial posterior parietal cortex. Significant between-group differences in activation were evident in a cluster spanning the medial frontal cortex and right precuneus, with the ARMS groups showing less activation than controls but greater activation than first-episode psychosis (FEP) patients. These group differences were more evident at the most demanding levels of the task than at the easy level. In all groups, task performance improved with repetition of the conditions. However, there was a significant group difference in the response of the right precuneus across repeated trials, with an attenuation of activation in controls but increased activation in FEP and little change in the ARMS.

Conclusions

Abnormal neural activity in the medial frontal cortex and posterior parietal cortex during an SWM task may be a neural correlate of increased vulnerability to psychosis.

Cognitive models suggest that auditory verbal hallucinations arise through defective self-monitoring and the external attribution of inner speech. We used a paradigm that engages verbal self-monitoring (VSM) to examine whether this process is impaired in people experiencing prodromal symptoms, who have a very high risk of developing psychosis.

Method

We tested 31 individuals with an At-Risk Mental State (ARMS) and 31 healthy volunteers. Participants read single adjectives aloud while the source and pitch of the online auditory verbal feedback was manipulated, then immediately identified the source of the speech they heard (Self/Other/Unsure). Response choice and reaction time were recorded.

Results

When reading aloud with distorted feedback of their own voice, ARMS participants made more errors than controls (misidentifications and unsure responses). ARMS participants misidentified the source of their speech as ‘Other’ when the level of acoustic distortion was severe, and misidentification errors were inversely related to reaction times.

Conclusions

Impaired VSM is evident in people with an ARMS, although the deficit seems to be less marked than in patients with schizophrenia. Follow-up of these participants may clarify the extent to which the severity of this impairment predicts the subsequent onset of psychosis and development of positive symptoms.

Despite the increasing development of early intervention services for psychosis, little is known about their cost-effectiveness. We assessed the cost-effectiveness of Outreach and Support in South London (OASIS), a service for people with an at-risk mental state (ARMS) for psychosis.

Method

The costs of OASIS compared to care as usual (CAU) were entered in a decision model and examined for 12- and 24-month periods, using the duration of untreated psychosis (DUP) and rate of transition to psychosis as key parameters. The costs were calculated on the basis of services used following referral and the impact on employment. Sensitivity analysis was used to test the robustness of all the assumptions made in the model.

Results

Over the initial 12 months from presentation, the costs of the OASIS intervention were £1872 higher than CAU. However, after 24 months they were £961 less than CAU.

Conclusions

This model suggests that services that permit early detection of people at high risk of psychosis may be cost saving.

Cognitive models propose that faulty appraisal of anomalous experiences is critical in developing psychosis, particularly delusions. A data gathering bias may be fundamental to abnormal appraisal

Aims

To examine whether there is a data gathering bias in people at high risk of developing psychosis

Method

Individuals with an at-risk mental state (n=35) were compared with a matched group of healthy volunteers (n=23). Participants were tested using a modified version of the ‘beads' reasoning task with different levels of task difficulty

Results

When task demands were high, the at-risk group made judgements on the basis of less information than the control group (P < 0.05). Within both groups, jumping to conclusions was directly correlated with the severity of abnormal beliefs and intolerance of uncertainty (P<0.05). In the at-risk group it was also associated with impaired working memory (P<0.05), whereas in the control group poor working memory was associated with a more conservative response style (P<0.05)

Conclusions

People with an at-risk mental state display a jumping to conclusions reasoning style, associated with impaired working memory and intolerance of uncertainty. This may underlie a tendency to develop abnormal beliefs and a vulnerability to psychosis

Cognitive models of psychosis suggest that whether anomalous experiences lead to clinically relevant psychotic symptoms depends on how they are appraised, the context in which they occur and the individual's emotional response

Aims

To develop and validate a semi-structured interview (the Appraisals of Anomalous Experiences Interview; AANEX) to assess (a) anomalous experiences and (b) appraisal, contextual and response variables

Method

Following initial piloting, construct validity was tested via cross-sectional comparison of data from clinical and non-clinical samples with anomalous experiences. Interrater reliability was also assessed

Results

Scores from AANEX measuring appraisals, responses and social support differentiated the clinical and nonclinical groups. Interrater reliability was satisfactory for 65 of the 71 items. Six items were subsequently amended

Conclusions

The AANEX is avalid multidimensional instrument that provides a detailed assessment of psychotic-like experiences and subjective variables relevant to the development of a need for clinical care

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